A series of separate electric circuits controlled by a single selector switch may be found in numerous electric and electronic devices, for example, a t.v. channel selector, automatic computer registers, dial telephone devices, etc. It is to the advantage of the units if the switch arrangement is essentially maintenance free, as a number of switches or relays may be ganged together and it is difficult to replace a single damaged switch.
A number of automatic dial systems for telephones have been proposed in the prior art, and these generally use wiper contacts for activating the circuits necessary for the dialing unit. Among the devices using a gang of switches or relays are the following examples:
Rickard U.S. Pat. No. 2,995,726 uses a loose leaf book with a selector attached to the book cover. Each page includes a contact for closing when the book is opened to that page. By using progressively cut away sheets, the selector may open the book to the selected page, and a wiper arm on the selector physically touches the page contact to close the circuit.
Brodie U.S. Pat. No. 3,531,599 uses a matrix of columns of switches and rows of switches. The switches are open contact subject to activation by the physical touching of moving contacts of wipers for each row. These are moved by electro-mechanical means causing the moving contact to be stopped from one to the next fixed contact.
Shio U.S. Pat. No. 4,010,330 discloses a gang of open contacts wiped by a moving contact. Each open contact is connected to an interchangeable circuit module, having a predetermined telephone number, for actuating the dialing apparatus.
British Pat. No. 1,219,547 describes a hinged cover, multiple page list. Each page is arranged with a switch which actuates when the cover is opened to that page. The multiple cover releases include a switch related to the coded lines of each page. The opening of the cover pivots one of a gang of wipers, and the wiper in line with the contact of the displaced page touches the contact, closing that circuit (to a memory). A push of the cover releases a button related to the desired line on the displayed page and activates that circuit which contains the pre-recorded number. This actuates automatic dialing apparatus.
Applicant's U.S. Pat. No. 4,163,360 describes an automatic dial telephone also using a hinged cover arranged to open to a particular page matching a particular computer register. A button at the side of the page activates a circuit of the address of the particular register containing the dialing information for the automatic dialer. The telephone finder list includes an open contact for each page of the telephone index and a touching wiper to close the circuit for activation.